// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Support for sanitizers. See runtime/cgo/sigaction.go.

//go:build (linux && amd64) || (freebsd && amd64) || (linux && arm64) || (linux && ppc64le)

package runtime


// _cgo_sigaction is filled in by runtime/cgo when it is linked into the
// program, so it is only non-nil when using cgo.
//go:linkname _cgo_sigaction _cgo_sigaction
var _cgo_sigaction unsafe.Pointer

func sigaction( uint32, ,  *sigactiont) {
	// racewalk.go avoids adding sanitizing instrumentation to package runtime,
	// but we might be calling into instrumented C functions here,
	// so we need the pointer parameters to be properly marked.
	// Mark the input as having been written before the call
	// and the output as read after.
	if msanenabled &&  != nil {
		msanwrite(unsafe.Pointer(), unsafe.Sizeof(*))
	if asanenabled &&  != nil {
		asanwrite(unsafe.Pointer(), unsafe.Sizeof(*))
	if _cgo_sigaction == nil || inForkedChild {
		sysSigaction(, , )
	} else {
		// We need to call _cgo_sigaction, which means we need a big enough stack
		// for C.  To complicate matters, we may be in libpreinit (before the
		// runtime has been initialized) or in an asynchronous signal handler (with
		// the current thread in transition between goroutines, or with the g0
		// system stack already in use).

		var  int32

		var  *g
		if mainStarted {
			 = getg()
		 := uintptr(unsafe.Pointer(&))
		switch {
		case  == nil:
			// No g: we're on a C stack or a signal stack.
			 = callCgoSigaction(uintptr(), , )
		case  < .stack.lo ||  >= .stack.hi:
			// We're no longer on g's stack, so we must be handling a signal.  It's
			// possible that we interrupted the thread during a transition between g
			// and g0, so we should stay on the current stack to avoid corrupting g0.
			 = callCgoSigaction(uintptr(), , )
			// We're running on g's stack, so either we're not in a signal handler or
			// the signal handler has set the correct g.  If we're on gsignal or g0,
			// systemstack will make the call directly; otherwise, it will switch to
			// g0 to ensure we have enough room to call a libc function.
			// The function literal that we pass to systemstack is not nosplit, but
			// that's ok: we'll be running on a fresh, clean system stack so the stack
			// check will always succeed anyway.
			systemstack(func() {
				 = callCgoSigaction(uintptr(), , )

		const  = 22
		if  ==  {
			// libc reserves certain signals — normally 32-33 — for pthreads, and
			// returns EINVAL for sigaction calls on those signals.  If we get EINVAL,
			// fall back to making the syscall directly.
			sysSigaction(, , )

	if msanenabled &&  != nil {
		msanread(unsafe.Pointer(), unsafe.Sizeof(*))
	if asanenabled &&  != nil {
		asanread(unsafe.Pointer(), unsafe.Sizeof(*))

// callCgoSigaction calls the sigaction function in the runtime/cgo package
// using the GCC calling convention. It is implemented in assembly.
func callCgoSigaction( uintptr, ,  *sigactiont) int32